Read-only memory is a type of non-volatile memory that does not lose stored data on being power cycled. One-time programmable (OTP) memory is a form of programmable read-only memory in which data is stored permanently and cannot be modified. In other words, OTP memory can only be programmed to store data once, and the stored data cannot be rewritten/overwritten. A typical OTP memory cell starts off with all bits reading ‘1’. An electric signal is used to burn a fuse that effectively allows setting of each bit of an OTP memory cell. That is, burning a fuse using the electrical signal may cause the bit to read ‘0’. The memory is programmed by blowing fuses.
Another category of non-volatile memory is reprogrammable read-only memory that is extensively used in, for example, security applications, fast computing applications, military applications, etc. The data stored in the memory cells of reprogrammable memory are re-erasable and re-usable. Examples of reprogrammable read-only memory include multiple time programmable (MTP) memory or few time programmable (FTP) memory. Erasable programmable read-only memory (EPROMs), electrically erasable programmable read-only memory (EEPROMs), flash EPROMS, etc., are examples of MTP memory.